Screw-cutting die.



- P.,H. COOK.-

SOEEW CUTTING DIE.

APPLICATION FILED M\AR.26, 1909; v

v Patented Feb. 18, 1913.

INVENTOR.

' ATTORNEY.

rinrrno s'rar FRANK H. COOK, OF GREENFIELD, MASSACHUSETTS.

SCREW-CUTTING DIE.

To all whom, it may; concern Be it known that I, FRANK H. Coon, a citizen of the United States of America, r'esiding at Greenfield, in the county of Franklin andiState of Massachusetts, have inventednew and useful Improvements inScrew- Cutting Dies, of which the following is a specification. m

This-invention relates to improvements 1n 'whichis being cut, and a second chip is removed from the other side of the tooth.

My invention has, as its objects,-(l) to provide a single land or die which will of itself, by reason of the shapeof the'cutting' teeth, form a perfect thread; (2) to provide the land with a set of leading teeth so formed that the teeth thereof are on a sharper angle or greater incline than the finishing teeth; (3) t0 so arrange the fin shing teeth that, preferably, every third tooth is omitted whereby space is provided for receiving the removed chips during the threadforming process; (4) to e fect, the formation of the finished threads whereby the apex of each toothiis left clean and sharp, that is without .any bur or rough edge.

Otherobjects and advantages will appear in the' body of the specification and will be particularly pointed out in the bl'aims.

In the drawings forming part of this applicatio-n,-l igure 1 is a vertical sectional view on the line 1-1, Fig. 2, showing the "cutting dies of lands arranged in the holding means. Fig. 2 is a plan View showing @the arrangement ofthe cutting die in the holding stock and with the set screws for securing the same in place. Fig. 3is an enlarged detail view illustrating the manner in which the cutting die is used.

Referring to the drawings in detail, a designates the usual die-stock provided with the operating handles 6.

c designa-testhe cutting dies that are retained in the. die-stock a by means of the setscrews (Z, for example, although other means may of course be employed for effecting the purpose.

Referring to Fig. The work in which a thread is being cut is designated by e and is Specification of Letters Patent; Patented. Feb. 18, 1913,

Application filed March 25, 1909. Serial No. 485,749.

supposed to represent metal. The threadcutting die 0, itwill be noticed, has at the '1naybe termed the leading teeth of the die,

that is, they do not cut the'full depth of the thread at once but merely block out, as it were, a path or track for the finishing teeth to follow. These teeth are formed with sharper sides or angles than the finishing teeth, as indicated at f and The finishing teeth are shown at hand i, and j designates a space between two of these teeth, or in other words one of the finishing teeth is omitted.

Referring to the finishing tooth i of the 7.

a of the following teeth It is removing. a

chip from the opposite side of the thread that 18 being cut, as shown at n. The angle between the cutting edges k and k is of -course the angle of the apex of the finished thread or the standard as shown and designated at m cutting edges 76 and h is the same as the space which, as shown, is 60 or the same as the angle between the sides of the finished toot-h, as shown at m and equal to the linear dimension of twoteet-h. Further, it will be noticed that the angle between the non-cutting edges of the teeth in and i is less than the angle m ofthe finished tooth, as shown at 0. This formation of the die-cutting teeth therefore permits the root portion of the thread p which is being cut to be carefully cut, as shown at 9. One of the functions of the space j of the die or land is to receive the chips thatdmve been removed from the stock or work by the cutting edges la and if. It is obvious that as long as the removed metal is retained in the space 7' or chip-receiving receptacles, that they can not injure the finished surfaces 1 and s or abrade the point t of the thread while being finished, thus leaving the thread that has been cut in the work clean and sharp on all of its surfaces. H

The arrow u desi' ates the direction in which the thread-cutting die '0 is moved, and it will be seen that several of the cut-ting teeth act on the work e for forming the finished threads.

A particular feature of this cutter lies in ES/PATENT OFFICE. I

The angle between the the fact that byreason, of the opening'y' for receiving the chips lessfrictio'n or power s required tocut a thread than in the ordl portion'of the tool thereof.

nary thread-cutting'die, wherein all of the thread-cutting teethrare used at one time; and, further, from the fact that only one side of each tooth is being formed during the ,cutting operation.

Although I am awarethat thread-cutting dies have heretofore been used in which op- I posite sides of-the tooth are acted upon in dependently, I consider it' new, as far as I am aware, to remove one of the cutting teeth for producing a chip-receiving reoeptacl'e for receiving the metal which has been 1 removedduring the cutting operation;

This improvement is equally applicable and-valuable as a chaser to be usedsingly for cutting threads in a lathe; that is to say, a single land or chaser is a complete toolin' itself, and can be used singly as a chaser or in sets, as'a die. The same idea is also applicable to taps, particularly large sizes, where the lands are inserted in the, body The threadforming teeth It and 't' with the spaces 7' ranged in pairs.

What'I claim, is: i 1 T ,1. In a cutting tool of the classdescrib'ed, asingle die, Orland member",- the cutting therebetween may be considered as being'arteeth of which are formed with angles or "different pitch on their opposite sides, and

the-sides of the spaces being arranged at'an rangle equal to the finished teeth whereby a I finishing chipis removed'fr om the'opposite 4e sides of the adjacent teeth being cut.

the teeth being so arranged that a space equalto the linear dimension of two cutting te'ethis formed between two successive teeth,

I 2. A thread-forming tool hafving a'dvanc-I ing teeth at the, forward end thereof, and pairs of thread-forming teeth for removing I a chip in succession from opposite SidGS'Of the thread being cut, said"pair s of teeth being arranged-so asto form an angular ,space between the thread 'fo'rming" teeth, said utool comprising asingleland or die member,

\ one -e 'ge only of which is provided with thread-formingteeth. y

3. A thread-forming tool having a single row of cutting teeth in the same plane, said teeth having their cutting edges arranged with an acute angularspace therebetween so as to operate simultaneously on the opposite sides of adjacent threads which are being formed, and the angle between the cutting'edges of the cutting-teeth being equal edges of the cutting teeth-being equal to the angle between the sides of the finished tooth, said cutting tool having ts teeth arranged with an angular space therebetween the sides .of which form an angleuequal to the sides of the finished tooth, whereby a chip is,

simultaneously removed from two different 5. thread-forming [tool comprising a single row of cut'tingrteeth, the advancing end of the tool having mutilated teeth. of less pitch than the tooth to becut, the finishing teeth of the tool having an angle -between two of its cutting teeth .that'is less than .thefinished angle of the thread which is being cut, whereby the root portion of the thread formed, and said cutting-teethhaving their opposite sides formed. as out ting edges that lare formed with. angles equal v A to the angles of the finished teeth of the thread.

1 '6. A thread-cutting die having two pairs i of cutting teeth, the angles of the outer sides I of two teeth of each pair being formed to re move'the finishing cut, the angle between the teeth in each pairof teeth being less than [the finishing angle of a tooth at its apex,

the adjacentcutting sides of the first mentioned angles of the two pairs of cutting teeth being prolonged so as to intersect in an-angle that representsflthe angle at the apex of the finished tooth, whereby a. space isformed between the two pairs of cutting teeth, and whereby the opposite sides of the adjacent teeth are cut in succession by. the

"outer sides of each pair of teethysubstan tially as described. i

7, A thread forming die having its teeth located in the same plane and arranged in groups of two, the angle between the teeth in each group 'therebetween being less than the finished thread, and the spaces between the groups being equal to the linear dimenj sions of two teeth, thesides of these'spaces being formed on angles equal to the angles of the finished thread, as described.-

Witne'sses V CHARLES L. Goon, HENRY H'IGINBOTHAM.

FRANKH. ooo 

